Hi,

I was able to do this using an UltraToolTipManager and some code in the MouseMove event of the OptionSet. Here's the code I used:

        UIElement lastElement = null;
        private void ultraOptionSet1_MouseMove(object sender, MouseEventArgs e)
        {
            // Get the OptionsSet
            UltraOptionSet optionSet = (UltraOptionSet)sender;

            // Get the UIElement that the mouse is currently over. 
            UIElement element = optionSet.UIElement.ElementFromPoint(new Point(e.X, e.Y));

            // If this is the same element we got the last time we were in MouseMove, 
            // ignore it. 
            if (element == this.lastElement)
                return;

            // Store the last element the mouse was over so we don't show the tooltip
            // repeatedly. 
            this.lastElement = element;

            // Get hte ToolTipInfo for the OptionSet control. 
            UltraToolTipInfo toolTipInfo = this.ultraToolTipManager1.GetUltraToolTip(optionSet);

            // See if the element is an Image
            ImageUIElement imageElement = element as ImageUIElement;           

            // If it's not an image, just clear the tooltip and bail out. 
            if (imageElement == null)
            {
                this.ultraToolTipManager1.HideToolTip();
                toolTipInfo.ToolTipText = string.Empty;            
                return;
            }

            // If the element is an image, get the associated ValueListItem
            ValueListItem item = imageElement.GetContext(typeof(ValueListItem)) as ValueListItem;
            if (item != null)
            {
                // If we get here, we know that the mouse is over an ImageUIElement inside
                // an item on the OptionSet. So set the ToolTipText.
                toolTipInfo.ToolTipText = item.DisplayText;
            }
        }